The present invention relates to a device for automatically opening/closing an optical path of a finder optical system of a camera.
Many cameras are provided with TTL-photometry type automatic exposure mechanism in which a photometry light-receiving element is provided within the main body of the camera. The quantity of the light entered through an objective lens is metered by the photometry light-receiving element, and a diaphragm is automatically adjusted.
In the case of a camera, such as a single-lens reflex camera, in which there is a partial overlap between the optical path of a finder optical system and the optical path of an image pick-up optical system, if a shutter release button is pressed while the photographer's eye is remote from a finder eyepiece window, e.g. the shutter release button is remotely operated while the camera is fixed on a tripod, the light entered from the finder eyepiece window affects the light-receiving element, obstructing the metering of the quantity of light. As a result, the diaphragm is erroneously adjusted.
In the case of another type of camera which uses a pellicle mirror as the major mirror and does not cause the mirror to swing up, if the shutter release button is pressed while the photographer's eye is remote from the finder eyepiece window, a fog occurs (which is caused by the light inversely entered from the finder eyepiece window while a film is exposed to the light of an object with the shutter being released), resulting in overexposure in some cases.
To prevent these problems, an eyepiece shutter is provided for the finder eyepiece window to prevent light from entering into the camera through the finder eyepiece window.
To close the finder eyepiece window through use of the conventional eyepiece shutter, various manual operations are required. It is necessary to press the shutter release button as well as to manually close the eyepiece shutter, rendering the operation of the camera very inconvenient.